Performance Tips
================

Performance tips for software rendering:

#. Turn off smooth shading when you don't need it (``glShadeModel``)
#. Turn off depth buffering when you don't need it.
#. Turn off dithering when not needed.
#. Use double buffering as it's often faster than single buffering
#. Compile in the X Shared Memory extension option if it's supported on
   your system by adding ``-DSHM`` to CFLAGS and ``-lXext`` to XLIBS for your
   system in the Make-config file.
#. Recompile Mesa with more optimization if possible.
#. Try to maximize the amount of drawing done between glBegin/glEnd
   pairs.
#. Use the ``MESA_BACK_BUFFER`` variable to find best performance in
   double buffered mode. (X users only)
#. Optimized polygon rasterizers are employed when

   - rendering into back buffer which is an XImage RGB mode,
     not grayscale, not monochrome

   - depth buffering is ``GL_LESS``, or disabled

   - flat or smooth shading dithered or non-dithered

   - no other rasterization operations enabled
     (blending, stencil, etc)

#. Optimized line drawing is employed when

   - rendering into back buffer which is an XImage RGB mode,
     not grayscale, not monochrome depth

   - buffering is ``GL_LESS`` or disabled

   - flat shading dithered or non-dithered

   - no other rasterization operations enabled (blending,
     stencil, etc)

#. Textured polygons are fastest when

   - using a 3-component (RGB)

   - 2-D texture minification and magnification filters are ``GL_NEAREST``

   - texture coordinate wrap modes for S and T are ``GL_REPEAT`` ``GL_DECAL``

   - environment mode ``glHint( GL_PERSPECTIVE_CORRECTION_HINT,
     GL_FASTEST )``

   - depth buffering is ``GL_LESS`` or disabled

#. Lighting is fastest when:

   - Two-sided lighting is disabled

   - ``GL_LIGHT_MODEL_LOCAL_VIEWER`` is false

   - ``GL_COLOR_MATERIAL`` is disabled

   - No spot lights are used (all ``GL_SPOT_CUTOFFs`` are 180.0)

   - No local lights are used (all position W's are 0.0)

   - All material and light coefficients are >= zero

#. XFree86 users: if you want to use 24-bit color try starting your X
   server in 32-bit per pixel mode for better performance. That is,
   start your X server with ``startx -- -bpp 32`` instead of ``startx -- -bpp
   24``
#. Try disabling dithering with the ``MESA_NO_DITHER`` environment
   variable. If this env var is defined Mesa will disable dithering and
   the command ``glEnable(GL_DITHER)`` will be ignored.